Single-Photon Detector Sub-Depletion Structure for Noise Reduction
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Solution Overview
Problem
Avalanche photodiodes and single-photon avalanche diodes suffer from noise signals due to electrons generated by surface defects, which are multiplied and contribute to unwanted noise.
Innovation Solution
The single-photon detection device incorporates sub-depletion regions and a guard ring region to prevent electrons or holes generated by surface defects from reaching the main depletion region, thereby reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high bias voltage is applied to provide avalanche multiplication gain, then detection sensitivity is improved, but noise signals from surface defects are amplified
Solution Approach 1:
The device segments the depletion region into a main depletion region and sub-depletion regions separated by intermediate wells. This segmentation prevents surface-generated noise carriers from reaching the main depletion region while preserving avalanche multiplication in the main depletion region for photon detection.
Solution Approach 2:
Intermediate wells are introduced as intermediary structures between the surface and the main depletion region. These wells act as barriers that block noise carriers generated at the surface from reaching the main depletion region, while allowing the main depletion region to maintain high electric field for photon detection.
2Object-generated harmful factors
If the depletion region is extended toward the surface to reduce surface defect impact, then noise is reduced, but detection efficiency decreases
Solution Approach 1:
The depletion region is segmented into a main depletion region positioned away from the surface and sub-depletion regions closer to the surface, separated by intermediate wells. This allows the main depletion region to maintain optimal position for detection while sub-depletion regions handle surface defect mitigation.
Solution Approach 2:
The device uses vertical layering with multiple wells at different depths to solve the two-dimensional conflict between noise reduction and detection efficiency. The intermediate wells are positioned at specific depths to block surface noise while maintaining photon detection capability in the main depletion region.
3Object-generated harmful factors
If intermediate wells are introduced to block noise carriers, then noise is reduced, but device structure becomes more complex
Solution Approach 1:
The device structure is segmented into alternating layers of p-type and n-type wells, creating a periodic structure that blocks noise carriers. This segmentation achieves noise reduction through a systematic pattern rather than ad hoc modifications.
Solution Approach 2:
The intermediate wells are designed with specific doping concentrations and depth positions that are optimized to block noise carriers while maintaining device performance. By carefully controlling these parameters, the structure achieves noise reduction without excessive complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device achieves low noise operation by minimizing noise signals from surface defects, enhancing the reliability and accuracy of single-photon detection.
Implementation Method 1
additional electron-hole pairs are sequentially generated due to impact ionization caused by the accelerated electrons
Implementation Method 2
avalanche multiplication of photo-generated carriers and an output current occurs
Implementation Method 3
sub-depletion regions and a guard ring region to prevent electrons or holes generated by surface defects from reaching the main depletion region
Data Source
AI summary
A single-photon detection device includes a first well having a first conductivity type, a second well provided on the first well and having a second conductivity type that is different from the first conductivity type, a first depletion forming region provided on the second well and having the first conductivity type, a main depletion region provided between the first well and the second well, and a first sub-depletion region provided between the second well and the first depletion forming region, wherein the first well and the first depletion forming region are spaced apart from each other by the second well.